Trolley system for a railway boxcar door

ABSTRACT

A trolley system for positioning the door of a railway boxcar to cover or uncover an opening in a wall of the boxcar has an upper track mounted to the boxcar and an upper trolley with at least one roller rotatably secured therein and co-acting with the upper track. A safety plate restricts the vertical motion of the roller to prevent derailment of the trolley from the track. The safety plate may include various designs to maximize the retention of the wheel against the track. A boxcar utilizing either a simple sliding door or a sliding door having a plug-type door associated with it may utilize this trolley system.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/457,416 filed Mar. 25, 2003 and U.S. Provisional Application No.60/494,534 filed Aug. 12, 2003, which are hereby incorporated byreference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention relates to railroad cars and, more particularly,to a trolley system for positioning the door of a railway car.

2. Description of Related Art

Railway boxcars typically include sliding doors which are doors whichroll along a track to cover and uncover a similarly-shaped openingwithin the boxcar. Plug-type doors are similar to sliding doors becausethey roll along a track on the boxcar to cover or uncover an openingwithin the railway boxcar. However, plug-type doors additionally moveaxially in and out relative to the wall of the boxcar to not only coverthe opening, but, furthermore, to seal the opening. The plug-type doorattaches to a frame and rolls on upper and lower tracks. A crankmechanism is used to displace the door axially toward and away from theboxcar wall to seal and unseal the door opening. Plug-type doors,hereinafter referred to as “plug doors”, were designed over fifty (50)years ago and, over the years, the American Association of Railroads(“AAR”) developed standards and rules for plug door designs so that theindustry had one uniform plug door design on the market. This eliminatedthe necessity of carrying many different parts to support the plug doordesigns of different manufacturers.

Today, the plug door design is essentially the same as it was fifty (50)years ago. Unfortunately, this design does not meet the current needs ofindustry. For example, occasionally the plug door becomes stuck and aforklift truck must be used to overcome this resistance and position theplug door. However, the force imparted by the fork lift tends to bendand damage the door. Additionally, racks which are transported in andout of the boxcar tend to hit and damage the door. Furthermore, the doorbecomes stressed from continual opening and closing. As a result, overtime the door and the door support mechanism become stressed and themechanism becomes more difficult to operate. Additionally, the plug dooris operated by a crank mechanism and when the door support mechanismbecomes difficult to operate, the crank mechanism may also be difficultto operate. In some instances, fork trucks and racks may hit the insideof the door causing pins within the door support mechanism to shearwhich, in turn, may cause the door to fall from the boxcar.

Attempts have been made to address these present problems by applyingstickers to the plug doors warning that opening the door improperly maycause it to fall. It is currently recommended that plug doors beinspected prior to opening to ensure that the door is properly supportedand may be opened safely.

While this problem has been described in relation to plug doors onrailway boxcars, it should be appreciated that similar problems existwith simple sliding doors on railway boxcars. Therefore, it is an objectof the subject invention to overcome these deficiencies in the priorart.

SUMMARY OF THE INVENTION

The subject invention is a trolley system for positioning the door of arailway boxcar in response to the rail and boxcar industry demand forsafety. The subject invention is also a mechanical device for openingand closing the doors associated with these railway cars.

In one embodiment of the subject invention, a trolley system forpositioning the door of a railway boxcar to cover or uncover an openingin a wall of the railway boxcar opening has an upper track mounted uponthe railway boxcar and an upper trolley having a body with at least oneroller rotatably secured therein, wherein the at least one roller of theupper trolley co-acts with the track. A safety plate is connected to therailway boxcar and positioned above and adjacent to the at least oneroller of the upper trolley, wherein the plate physically limits thevertical movement of the roller in the upper trolley to preventderailment of the upper trolley from the upper track.

In another embodiment of the subject invention, a railway boxcar has abase with railway boxcar rollers secured to the base and an enclosureattached to the base, wherein the enclosure has a door opening. An uppertrack is defined at an upper portion of the enclosure adjacent the dooropening. The upper track has a U-shaped cross section. A lower track isdefined at a lower portion of the enclosure adjacent the door openingand has a U-shaped cross section. An upper cage surrounds the uppertrack and a lower cage surrounds the lower track. An upper trolleyco-acts with the upper track and has a body with at least one rollerhaving a U-shaped cross section. A lower trolley co-acts with the lowertrack and has a body with at least one roller having a U-shaped crosssection. A frame is attached to the upper carriage and the lowercarriage. The frame and the carriages are adapted to move along theupper track and the lower track. A door is attached to the frame andadapted to move axially relative to the frame. The door, when alignedwith the door opening, is adapted to move axially in a first position toseal the door opening and prevent movement of the frame relative to thetracks. When the door is axially moved to a second position, the door isadapted to move away from the door opening so that the frame and doormay move laterally along the tracks to expose the door opening. A crankco-acts with the frame and the door to move the door in the firstposition and the second position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view sketch of a railway boxcar for the purposesof introducing the subject invention;

FIG. 2 is a front elevational view of a railway boxcar similar to thatshown in FIG. 1;

FIG. 3 is a side elevational view, partially in section, of the railwayboxcar along arrows “3-3” illustrated in FIG. 2;

FIG. 4 shows a front elevational view of a railway boxcar made inaccordance with a second embodiment of the subject invention;

FIG. 5 is a side elevational view of the railway boxcar illustrated inFIG. 4;

FIG. 6 is a top view of the trolley and offset arm with the plug door inthe open position;

FIG. 7 is a top view of the trolley and the offset arm with the plugdoor in a closed position;

FIG. 8 is a perspective view of the trolley body in FIGS. 4 and 5;

FIG. 9 is a partial sectional view of a portion of the trolley furtherillustrating a safety and weather shield;

FIG. 10 is a perspective view of the offset arm in accordance with thesubject invention;

FIG. 11 is a perspective view of the bottom guide in accordance with thesubject invention;

FIG. 12 illustrates a side view of a support member having a bent bottomarm;

FIG. 13 is a top view of the same side arm illustrated in its positionrelative to the door;

FIG. 14 is a side view of a support member having a straight bottom;

FIG. 15 is a top sectional view of the support member in FIG. 14illustrating its relative position to the door;

FIG. 16 is a side elevational view of a portion of a third embodiment ofthe subject invention;

FIG. 17 is a side elevational view of a portion of a fourth embodimentof the subject invention;

FIG. 18 is a side elevational view of a portion of a fifth embodiment ofthe subject invention;

FIG. 19 is a front elevational view of a sliding door (non plug-typedoor) utilizing the trolley system in accordance with the subjectinvention;

FIG. 20 is an end view of one trolley illustrated in FIG. 14;

FIG. 21 is an end view of one lower guide illustrated in FIG. 14;

FIG. 22 is a perspective view of a safety arm that may be used with thetrolley system; and

FIG. 23 is an end view of the safety arm illustrated in FIG. 19positioned within the confines of the upper trolley body.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a perspective view showing a railway boxcar 10 havinga base 12 with wheels 14 attached thereto. A boxcar enclosure 16 isattached to the base 12 and includes an opening 18 through a wall 20 ofthe enclosure 16. Typically, the boxcar 10 is rectangular in shape. Theopening 18 in a wall 20 of the boxcar 10 may be covered or uncovered bya door 22. In particular, the trolley system for positioning the door 22of the railway car 10 to cover or uncover the opening 18 in a wall 20has an upper track 30 mounted upon the boxcar 10 and a lower track 35also mounted upon the boxcar 10. The upper track 30 engages an uppertrolley to support the door 22. The lower track 35 engages a lower guide(not shown) attached to the door 22. While FIG. 1 illustrates a door 22that appears to have no other motion but for lateral motion providedwithin the upper track 30 and the lower track 35, it should beappreciated and, as will be shown, the door 22 may also be capable ofmotion in a direction perpendicular to the plane of the door 22 so thatthe door 22 may be used to plug and unplug the opening 18.

FIGS. 2 and 3 illustrate an embodiment of the subject invention, wherebythe door 22 is secured to the wall 20 of a boxcar 10 through an uppertrack 30 and a lower track 35 mounted upon the boxcar 10. It should benoted that FIG. 2 is a generalized view while FIG. 3 is an accuraterepresentation of a sectional view of FIG. 2. A frame 48 supports thedoor 22 relative to the upper trolley 40 which rides in the upper track30 and the lower guide 45 which rides in the lower track 35. A crankmechanism 50 rotates a power screw 52 which urges the door 22 into oraway from the opening 18 of the boxcar 10. Additionally, the door 20 maymove laterally along the upper track 30 and lower track 35 to positionthe door 22 away from the opening 18 or in alignment with the opening18.

The upper trolley 40 has a body 60 with at least one roller 62 rotatablysecured therein. The at least one roller 62 of the upper trolley 40co-acts with the upper track 30. As illustrated in FIG. 3, a similararrangement may exist for the lower guide 45 which, in this instance, isa lower trolley having a lower trolley body 65, with at least one roller67 rotatably secured therein. The at least one roller 67 of the lowertrolley body 65 co-acts with the lower track 35.

Directing attention again to FIG. 3, the roller 62 of the upper trolley40 has a concave outer surface 64 and the upper track 30 has a convexouter surface 32 which mates with the roller outer surface 64. Asillustrated in FIG. 3, the concave outer surface 64 of the roller 62 andthe convex outer surface 32 of the upper track 30 may be V-shaped. In apreferred embodiment to be discussed, the surfaces are U-shaped.

The upper track 30 is mounted upon the railway boxcar 10 at the wall 20and the upper track 30 may further include a bracket 34 which connectsthe upper track 30 to the wall 20. The bracket 34 may have a Z-shapesuch that the bracket 34 not only provides support to the upper track30, but, furthermore, acts to partially enclose the roller 62 of theupper trolley body 60.

Additionally, a safety plate 70 is connected to the railway car 10 atthe wall 20 and positioned above and adjacent to the at least one roller62. The plate 70 physically limits the vertical movement of the roller62 in the upper trolley 40 to prevent derailment of the upper trolleyroller 62 from the upper track 30.

The safety plate 70 includes a projection 72 extending from the top ofthe plate 70 to a location at least partially entering the groove 74defined by the concave outer surface 64 of the roller 62 to limit thevertical displacement of the roller 62. Utilizing such a design, theupper trolley roller 62 not only is positively retained against theupper track 30, but, furthermore, is retained within a partial enclosureprotecting the elements from the environment and, thereby, extending thelife of the trolley system.

In the embodiment illustrated in FIGS. 2 and 3, the lower guide 45 iscomprised of a lower trolley having similar characteristics to the uppertrolley 40 just described and, for that reason, it should be understoodthat the description applicable to the upper trolley 40 in FIG. 3 alsoapplies to the lower trolley or lower guide 45 illustrated in FIG. 3.The lower guide 45 directs the travel of the door 22 along a pathidentical to that in which the upper trolley 40 directs the door 22. Asupport member 80 connects the upper trolley 40 with the lower guide 45.Furthermore, the door 22 is connected to the support member 80. Betweenthe support member 80 and the door 22 is at least one axial guide 82which permits axial movement of the door 22 in a direction perpendicularto the plane of the door to plug or unplug the door opening 18. Theguide 82 permits axial sliding of the door 22 relative to the supportmember 80 as the door 22 is urged back and forth by the power screw 52of the crank mechanism 50.

Referring to FIG. 2, the frame 48 may be made up of a plurality ofsupport members 80 and, additionally, a plurality of horizontalreinforcing members 84 connected to the support members 80. The crankmechanism 50 in conjunction with the power screw 52 (FIG. 3) moves thedoor 22 along the axial guide 82 to plug or unplug the opening 18. Thedoor 22 may include a seal (not shown) about its perimeter, such thatthe door is sealed when moved into the plugged position.

Independent of the axial motion of the door 22 along the axial guide 82,the door 22 in the unplugged position may also be moved by the uppertrolley 40 in a lateral direction along the wall 20 of the boxcar 10 toexpose the opening 18 or to position the door 22 in alignment with theopening 18 such that the door 22 may be axially advanced to plug theopening 18.

The subject invention utilizes many common features of boxcar doors. Inmany instances, the trolley system herein described may be retrofittedonto existing boxcars with the addition of the upper track 30 and thelower track 35 secured to the wall 20 of the boxcar 10. For that reason,the subject invention can easily be provided in a kit form or,alternatively, a complete new door system could be providedincorporating the above-described invention.

The subject invention need not be used with only a plug door, but mayalso be used with a simple sliding railway car door. Furthermore, thesubject invention can be used with a single door in a double doorarrangement. In the simple sliding railway boxcar door, there would beno crank mechanism and the door would merely slide from side to sidealong the upper trolley.

The plug door 22 described in FIGS. 2 and 3 is a door 22 which, throughpure axial motion, is positioned in a plugged or unplugged state. Thereare other designs for positioning the plug door in the plugged orunplugged position, and attention will be given now to the applicationof the trolley system in accordance with the subject invention as it mayapply to these designs.

Another mechanism utilized for positioning the door 22 in a plugged orunplugged position involves the use of support members 80 attached tothe door 22, wherein the support members 80 are connected to the boxcarwith pivoting arms which swing the door 22 along an arcuate path from anunplugged position to a plugged position. During this process thesupport members 80 pivot. This pivoting motion translates into arotational motion for the support members 80 and this rotational motionmay be advantageously used as a driver to move the door 22 back andforth between the plugged and unplugged position.

Directing attention to FIGS. 4 and 5, a second embodiment of the subjectinvention is illustrated. It should be noted that FIG. 4 is ageneralized view while FIG. 5 is an accurate representation of asectional view of FIG. 4. An upper track 130 is mounted upon the wall120 of a boxcar 110. An upper trolley 140 has a body 160 with at leastone roller 162 rotatably secured therein. The at least one roller 162 ofthe upper trolley 140 co-acts with the upper track 130. A safety plate170 connected to the boxcar 110 is positioned above and adjacent to theat least one roller 162 of the upper trolley 140 such that the safetyplate 170 physically limits the vertical movement of the roller 162 inthe upper trolley 140 to prevent derailment of the upper trolley roller162 from the upper track 130. However, unlike the safety plateillustrated with respect to FIGS. 2 and 3, the safety plate 170 defines,in conjunction with the roller 162, a vertical distance D which is lessthan the vertical distance that would permit the roller 162 and theupper track 130 to become disengaged.

Directing further attention to the embodiment illustrated in FIGS. 4 and5, the door 122 is similar to the door 22 previously described, andincludes a frame 148 with support members 180 and horizontal reinforcingmembers 184. Connector rods 186, which are laterally extended andretracted by the crank mechanism 150, rotate the support members 180such that the direction of rotation of the support members 180 causesthe door 122 to move toward or away from the opening 118 of the railcarwall 120. A turnbuckle 183 may be used with a support member 180 toadjust the overall length of the support member 180 and the distancebetween the upper trolley 140 and a lower guide 145.

The top views of the trolley system provided in FIGS. 6 and 7 illustratethis pivoting motion which positions the door 122 in the plugged or theunplugged position. FIG. 6 illustrates the trolley system, wherein thedoor 122 is in an open position relative to the opening 118 (FIG. 5), ina fashion similar to that illustrated in FIG. 5. The support member 180is connected to the upper trolley 140 and to the lower guide 145. Whenviewed from the top as in FIG. 6, the body 160 of the upper trolley 140may have two rollers 167 attached thereto, which co-act with the uppertrack 130. The support member 180 includes a pivot guide 190 forimparting to the support member 180, and to the door 122 connectedthereto, an arcuate motion to plug and unplug the door opening 118. Forexample, FIG. 6 illustrates the door 122 spaced from the opening which,for purposes of a discussion, may be located directly beneath therollers 162, 167. The pivot guide 190 is pivotally attached to the uppertrolley body 160 and is rigidly attached to the support member 180.Therefore, with respect to FIG. 6, as the pivot guide 190 rotates in aclockwise direction, pivoting about point P on the upper trolley body160, the pivot guide 190 through the support member 180 moves the door122 along the arc A to the plugged position as illustrated in FIG. 7.

The upper track 130, upon which the roller 167 travels, extends alongthe boxcar 110 a length suitable to accommodate the desired lateralmotion of the door 122.

FIGS. 6 and 7 illustrate the door 122 in the unplugged and pluggedpositions. It should be appreciated that as the pivot guide 190 followsthe arc A, the support member 180 rotates about its longitudinal axis L.Therefore, by rotating the support member 180 about its longitudinalaxis L, the pivot guide 190 will pivot, thereby causing the supportmember 180 and the door 122 attached thereto to follow the arc A of thepivot guide 190. Stated differently, and with attention directed to FIG.4, the connector rods 186 are fastened in an offset manner to collars188 about the support member 180, such that translation of the connectorrods 186 causes each collar 188, along with each support member 180, torotate about the longitudinal axis L, thereby moving the door 122between the plugged and the unplugged positions. The crank mechanism 150imparts such lateral displacement to the connector rod 186, therebyproviding the prerequisite motion to position the door 122 in theplugged or unplugged position.

FIG. 8 is a perspective view of the upper trolley body 160 with rollers167 attached thereto. Integral with the upper body 160 is a limit arm166 which, as illustrated in FIG. 5, is intended to limit the travel ofthe door 122 away from the opening 118.

FIG. 9 illustrates the arrangement by which the pivot guide 190 of thesupport member 180 is secured to the upper trolley body 160. Inparticular, the bore 195 extending through the pivot guide 190 has akingpin 200 extending therethrough. The kingpin 200 is a cylindricalmember having a shoulder 202 at one end thereof and threads 204 at anopposite end. The kingpin 200 passes through the kingpin hole 168 of theupper trolley body 160 so that the shoulder 202 abuts against a lowersurface of the upper trolley body 160. The kingpin 200 is secured to theupper trolley body 160 with a washer 206 and a nut 208 which engages thethreads 204 of the kingpin 200. A cotter pin may extend through the nut208 to retain the nut 208 in the tightened position. The kingpin hole168 may be lined with a bushing 210 to promote longevity of the joint.The bushing 210 may be of a hardened material or of a composite materialhaving a surface with a level of lubricity to permit sliding.

FIG. 5 and FIG. 10 illustrate details of the pivot guide 190 and includethe kingpin receiving bore 195 defined in an upper portion 197 of thepivot guide 190. The upper portion 197 is axially spaced from andsecured to a lower portion 198 of the pivot guide 190. The upper portion197 is pivotally secured to the upper trolley body 160 and extendsthrough an opening 211 defined by the safety plate 170, which plate 170may also function as a safety and weather shield. The lower portion 198is rigidly secured to the support member 180 through a lower portionhole 199 defined in the pivot guide 190.

Briefly returning to the embodiment illustrated in FIGS. 2 and 3, thelower guide 45 in this particular embodiment is a lower trolleyessentially duplicating the upper trolley 40 whereby the roller 62 ofthe upper trolley 40 and the roller 67 of the lower trolley body 65 notonly share the weight load of the door 22 and associated frame 48, but,furthermore, each of the rollers 62, 67 is restrained by theirrespective support plate (70, for example) to limit the upward movementof the rollers 62, 67, thereby preventing derailment of the rollers 62,67 from the respective upper track 30 and lower track 35.

Briefly directing attention to the embodiment illustrated in FIGS. 4 and5, to the extent that the upper trolley 140 is capable of supporting theentire weight of the door 122 and the associated frame 148, then it isnot necessary for the lower guide 145 to support weight. It isnecessary, on the other hand, for the lower guide 145 to restrain thedoor 122 in the frame 148 such that it moves in a path similar to thepath dictated by the pivot guide 190.

Directing attention to FIGS. 5 and 11, the lower guide 145 includes aguide arrangement 215. As illustrated in these figures, the guidearrangement 215 utilizes an element 216 that may be a roller or asliding block. A roller would be able to rotate within the cage 232while a block would slide back and forth within the cage 232. Any blockused may have a surface with a level of lubricity that would permit suchsliding. A spacer 220 is secured to a body 222 of the guide arm 225. Ahole 227 is defined by the body 222 for receipt of a lower portion ofthe support member 180 as shown in FIG. 5. The body 222 passes through acage opening 230 defined by a cage 232. A gap 234 is defined between anupper portion of the guide arrangement 215 and a lower surface of anupper portion of the cage 232. In a fashion similar to that of thesafety plate 170 for the upper trolley 140, the cage 232 additionallymay be used to provide a safety and weather shield 236. As a result, thelower guide 145 has a non-weight bearing guide arm 225 which acts as aguide through the interaction of the guide arrangement 215 and thesupport member 180.

FIG. 5 illustrates an arrangement whereby the support member 180 isconnected to the door 122 with connector segments 182 which are rigidlyconnected to the door 122, but permit rotation of the support member 180therein. At the same time, the support member 180 provides verticalsupport to the door 122.

To reduce the overall width of a boxcar which implements the trolleysystem in accordance with the subject invention, it is possible to movethe support member 180 closer to the door 122. As illustrated in FIGS.12 and 13, the bottom portion of the support member 180 may have a bentbottom segment 238 which, in conjunction with a similar geometry for thepivot guide 190 (FIG. 5), permits the support member 180 to be placedmuch closer to the door 122 to the point where, as illustrated in FIG.13, the support member 180 may fit within a recess 124 within the door122. In the alternative, as illustrated in FIGS. 14 and 15, the supportmember 180 may be entirely straight, and, as a result, the supportmember 180 would be spaced a further distance from the door 122 throughextended connector segments 282.

FIGS. 16 and 17 illustrate different mechanisms whereby the wheel of thetrolley may be positively retained against the upper track.

In particular, and directing attention to FIG. 16, an upper trolley 340has similar features to upper trolley 140 and upper trolley 40previously discussed. However, the safety plate 370 which retains theroller 360 against the upper track 330 is made up of a projection 372having a matching V-shape to that V-shape of the roller 360. As aresult, the safety plate 370 retains the roller 360 against the uppertrack 330 such that it may not derail.

In the alternative, and as illustrated in FIG. 17, in which all of thefeatures are identical to those in FIG. 16, with the exception of thesafety plate 470, the safety plate 470 is essentially a flat pieceplaced close to the top of the roller 360, thereby, once again, limitingthe vertical movement of the roller 360, such that it may not derailfrom the upper track 330.

FIG. 18 illustrates an upper trolley 440 having all of the features ofthose upper trolleys previously discussed, with the exception that theprevious trolleys have wheels having a V-shaped groove compatible with amating V-shaped track. The upper trolley 440 illustrated in FIG. 18includes a roller 460 having an upper track 430 with a semi-circularshape to engage the roller 460. However, once again, the safety plate470 is positioned such that the roller 460 may not be verticallydisplaced to a level that would permit it to be derailed from the uppertrack 430. The safety plate 470 and platform 434 supporting the uppertrack 430 define a cage 432.

The trolley system so far discussed has been directed to an arrangementin conjunction with a plug door. However, as illustrated by FIG. 19, thetrolley arrangement may also be applied to a simple sliding door 522which does not have a plug door associated with it, but merely must movelaterally along an upper track 530. To that end, an upper trolley 540having features similar to any of the upper trolleys (40, for example)previously discussed herein may be utilized to provide a trolley that ispositively retained against the upper track, thereby minimizing thelikelihood of derailment. Additionally, a lower guide 545, similar tothe lower guides herein discussed, may be utilized. FIG. 20 illustratesan end view of the upper trolley 540 that may be utilized including anupper track 530, an upper trolley 540 having at least one roller 560secured therein, and a safety plate 570 which retains the roller 560 andprevents derailment from the upper track 530. Additionally, a lowerguide 545 incorporating a guide arrangement 515 captured within a cage532 provides a mechanism by which the door 522 tracks in a similar paththrough the upper trolley 540 and the lower guide 545.

With reference to FIG. 4, the door 122 may include at least one safetyarm 600. Details of the safety arm are illustrated in FIGS. 22 and 23.

The safety arm 600 is comprised of a frame 605 having an overhungportion 610 that is positioned vertically above the upper track 430 butlaterally spaced from an upper trolley 140 (FIG. 4). The frame 605 issecured to the door 122 at the frame base 607. As long as the door 122is properly supported by the upper trolleys 160, then the safety arm 600is suspended within the cage 432 of the upper trolley 440, i.e., theroller 460 (FIG. 18) is engaging the track 430. However, in the eventone or more upper trolleys 160 become derailed from the track 430, thedoor 122 will fall vertically only until the overhung portion 610 of theframe 600 engages the track 430 or the platform 434 supporting the track430. A projection 615 may extend from the frame 605 and would engage alip 472 of the safety plate 470 to further retain the frame 605 withinthe cage 432.

The trolley system described herein may be provided as a kit andcurrently existing boxcars may be retrofitted. In particular and withreference to FIG. 5, the guide tracks of an existing boxcar may beremoved and the upper track 130, safety plate 170, and the cage 232 maybe secured to the boxcar 122. Additionally the support member 180 may besecured through connector segment 182 to the door 122. The supportmember 180 is also secured to the upper trolley 140, which is upon theupper track 130 and to the guide arrangement 215, which is within thecage 232.

While specific embodiments of the invention have been described indetail, it will be appreciated by those skilled in the art that variousmodifications and alternatives to those details could be developed inlight of the overall teachings of the disclosure. The presentlypreferred embodiments described herein are meant to be illustrative onlyand not limiting as to the scope of the invention which is to be giventhe full breadth of the appended claims and any and all equivalentsthereof.

1. A trolley system for positioning the door of a railway boxcar tocover or uncover an opening in a wall of the railway boxcar comprising:a) an upper track mounted upon the railway boxcar; b) an upper trolleyhaving a body with at least one roller rotatably secured therein,wherein the at least one roller of the upper trolley co-acts with thetrack; and c) a safety plate connected to the railway boxcar andpositioned above and adjacent to the at least one roller of the uppertrolley, wherein the plate physically limits the vertical movement ofthe roller in the upper trolley to prevent derailment of the uppertrolley roller from the upper track.
 2. The trolley system according toclaim 1, wherein the at least one roller has a concave outer surface andthe upper track has a convex outer surface which mates with the rollerouter surface.
 3. The trolley system according to claim 2, wherein theat least one roller has a U-shaped outer surface and the track has amating U-shaped outer surface.
 4. The trolley system according to claim3, wherein the plate includes a projection extending from the top of theplate downwardly to at least partially enter the groove and to limit thevertical displacement of the roller.
 5. The trolley system according toclaim 3, wherein the at least one roller has a curved outer edge and thetrack portion in contact with the upper trolley is U-shaped.
 6. Thetrolley system according to claim 2, wherein the plate defines inconjunction with the roller a vertical distance which is less than thevertical distance that would permit the roller and track to becomedisengaged.
 7. The trolley system according to claim 6, wherein theplate further extends to generally enclose the upper trolley to act as asafety shield and to protect against the weather.
 8. The trolley systemaccording to claim 1, further including a door and a lower guide,wherein the lower guide directs the travel of the door along a pathidentical to that in which the upper trolley directs the door.
 9. Thetrolley system according to claim 8, wherein the upper trolley and lowerguide are connected directly to the door.
 10. The trolley systemaccording to claim 9, wherein: a) the system further includes a lowertrack mounted upon the railway boxcar below the door opening; b) thelower guide is a lower trolley having a body with at least one rollerrotatably secured therein, and wherein the at least one roller of thelower trolley co-acts with the lower track; and c) a safety plateconnected to the railway boxcar and positioned above and adjacent to theat least one roller of the upper trolley, and wherein the platephysically limits the vertical movement of the upper trolley to preventderailment of the upper trolley from the upper track.
 11. The trolleysystem according to claim 8, further including a support memberconnecting the upper trolley and lower guide, and wherein the door isconnected to the support member.
 12. The trolley system according toclaim 11, wherein: a) the system further includes a lower track mountedupon the railway boxcar below the door opening; b) the lower guide is alower trolley having a body with at least one roller rotatably securedtherein, and wherein the at least one roller of the lower trolleyco-acts with the lower track; and c) a safety plate connected to therailway boxcar and positioned above and adjacent to the at least oneroller of the lower trolley, and wherein the plate physically limits thevertical movement of the lower trolley to prevent derailment of thelower trolley from the upper track.
 13. The trolley system according toclaim 11, further including at least one axial guide between the doorand the support member to permit axial movement of the door in adirection perpendicular to the plane of the door to plug or unplug thedoor opening.
 14. The trolley system according to claim 11, wherein thesupport member further includes a pivot guide for imparting to thesupport member an arcuate motion which is also imparted to the door toplug and unplug the door opening.
 15. The trolley system according toclaim 14, wherein the pivot guide is an offset arm extending from thebody of the upper trolley to the support member.
 16. The trolley systemaccording to claim 15, wherein the offset arm is secured to the body ofthe upper trolley by a kingpin extending through both the offset arm andthe body of the upper trolley.
 17. The trolley system according to claim16, wherein the offset arm provides an arcuate motion to the door suchthat rotation of the support member by approximately 30 degrees willmove the door to plug and to unplug the door opening.
 18. The trolleysystem according to claim 14, further including a recess within the doorto accommodate the support member thereby minimizing the distance thesupport member extends away from the railway boxcar.
 19. The trolleysystem according to claim 8, wherein the upper trolley body furtherincludes a limit arm to limit the travel of the door from the closed tothe open position.
 20. The trolley system according to claim 8, furtherincluding a safety arm supported by the boxcar door, wherein the safetyarm has an overhung portion which is positioned vertically above theupper track such that the safety arm will engage the upper track or aplatform supporting the track if the door drops.
 21. A railway boxcar,comprising: a) a base; b) railway boxcar rollers secured to the base; c)an enclosure attached to the base, wherein the enclosure has a dooropening; d) an upper track mounted upon the railway boxcar; e) an uppertrolley having a body with at least one roller rotatably securedtherein, wherein the at least one roller of the upper trolley co-actswith the track; f) a plate surrounding the upper trolley and uppertrack, wherein the plate physically limits the vertical movement of theupper trolley to prevent derailment of the upper trolley from the uppertrack; g) a lower guide which directs the travel of the door along apath identical to that in which the upper trolley directs the door; h) aframe attached to the upper trolley and the lower guide; i) a doorattached to the frame, the door adapted to move axially relative to theframe, the door when aligned with the door opening adapted to moveaxially in a first position to seal the door opening and preventmovement of the frame relative to the tracks and when the door isaxially moved to a second position, the door is adapted to move awayfrom the door opening so that the frame and door may move laterallyalong the tracks to expose the door opening; and j) a crank co-actingwith the frame and the door to move the door in the first position andthe second position.
 22. A kit for assembling a trolley system forpositioning the door of a railway boxcar to cover or uncover an openingin a wall of the railway boxcar comprising: a) an upper track adapted tobe mounted upon the railway boxcar; b) an upper trolley having a bodywith at least one roller rotatably secured therein, wherein the at leastone roller of the upper trolley is adapted to co-act with the track; andc) a safety plate adapted to be connected to the railway boxcar andpositioned above and adjacent to the at least one roller of the uppertrolley, wherein the plate is positioned to physically limit thevertical movement of the roller in the upper trolley to preventderailment of the upper trolley roller from the upper track.
 23. The kitaccording to claim 22, further including a lower guide adapted to bemounted upon the railway boxcar below the door opening, wherein thelower guide is adapted to direct the travel of the door along a pathidentical to that in which the upper trolley directs the door.
 24. Thekit according to claim 23, further including a support member connectingthe upper trolley and the lower guide, wherein the support member isadapted to be connected with the door.
 25. A method of retrofitting aboxcar with a trolley system for positioning the door of a railwayboxcar to cover or uncover an opening in a wall of the railway boxcarcomprising the steps of: a) securing an upper track to the boxcar; b)positioning an upper trolley upon the upper track, wherein the uppertrolley has a body with at least one roller rotatably secured thereinand wherein the at least one roller of the upper trolley is adapted toco-act with the track; c) securing the door to the upper trolley; and d)securing a safety plate to the railway boxcar positioned above andadjacent to the at least one roller of the upper trolley, wherein theplate is positioned to physically limit the vertical movement of theroller in the upper trolley to prevent derailment of the upper trolleyroller from the upper track.
 26. The method according to claim 25,further including the step of securing a lower guide to the railway car,wherein the lower guide is connected to the upper trolley to direct thetravel of the door along a path identical to that in which the uppertrolley directs the door.